Guest Post by Willis Eschenbach
Anthony has discussed a paywalled study in the new reality-based Nature Magazine production, Nature Climate Change magazine. Unlike Anthony, they approved my application for a free subscription … go figure. The study is called “Nonlinear heat effects on African maize (corn) as evidenced by historical yield trials”, Lobell et al. (hereinafter L2011). The study looked at the effect of heat on corn production. Here’s their Figure 1:
Figure 1. The opening figure in the L2011 study of maize production in southern Africa. I always enjoy rich visual presentation of data, note that this contains elevation information as well.
Their conclusion? When it gets above a certain temperature, maize growth quickly slows, and it’s worse when it’s dry. Of course with the obligatory links to global warming and the danger of large drops in corn production. Shocking news, I know. They provided a citation to other scientists saying the same thing, in case you doubted it — too much heat is bad for plants. I bet the farmers of the world were as amazed as I was.
Or as they put it in their abstract:
Each degree day spent above 30° C [86°F] reduced the final yield by 1% under optimal rain-fed conditions, and by 1.7% under drought conditions. These results are consistent with studies of temperate maize germplasm in other regions, and indicate the key role of moisture in maize’s ability to cope with heat.
Now, we need to be careful here. They are not talking about the number of days where the temperature goes above 30°C. They are discussing “degree days”. That is the sum of the average daily temperature (C) less 30 degrees, for all the days where the average temperature [defined as (daily max + min)/2] is above 30°C. The figure is written as “GDD30+”, for “growing season degree days over 30°C”. They figure the growing season as 150 days, which agrees with the Texas figures given below.
Are their numbers accurate? Is there a drop in yield of 1% for every degree day as they claim? I don’t know. Haven’t done my homework yet, just dug up the paper, gimme a minute. Where do they grow corn? Iowa? Let me look it up. OK, I find:
Figure 2. Major (dark green) and minor (light green) corn growing areas in the US, by county. Texas is the large state numbered “2”. Between 60-70% of Texas corn is irrigated.
Fascinating. I love doing this, I get to learn so much. Well, at first glance I’d say the following:
1. The major corn-growing areas are from about 37°N to 47°N. So clearly, corn prefers temperate weather.
2. Corn is only a minor crop in many regions within that general preferred temperature band. So obviously, there’s other factors. The usual suspect would be water, second would be soil.
3. Corn is grown in the California Central Valley, one county in Arizona (irrigated, no doubt), a number of counties in southern Texas (mostly irrigated), and one county in Florida. I looked at the temperature record for Hidalgo County, the left one of the counties at the south tip of Texas in Figure 2. I looked at the daily temperature record for Edinburgh, in the middle of the county.
Here’s the curious thing. During the corn-growing season of 1999, the total number of “degree day[s] spent above 30° C” (GDD30+) in the Texas corn-growing area was 136 … so if yield dropped by 1% for each degree-day over 30°C, we’re down below zero to a quarter of the original yield. Hmmm. Figure 3 shows the degree day analysis, from the excellent online calculator from Wolfram Alpha here:
Figure 3. Degree days over 30°C for 150-day 1999 corn-growing season, Edinburgh, Texas.
I got to thinking about what was happening. How could they be growing corn in that kind of heat, with a GDD30+ over a hundred and thirty? I thought about it a while, and looked around on the web a bit. Figure 4 shows part of the answer:
Figure 4. Corn planting and harvesting dates in Texas. The “Panhandle” is the most northerly square section of the state (see Figure 2). SOURCE.
I’m sure you see the pattern. In the south, like Hidalgo County above, they plant and harvest early. Their crop is three-quarters harvested before the rest of the state has even begun.
As for the other part of the answer, I don’t know. I don’t know why even with their early growing season (March 1 – August 1) the Texas farmers are still able to grow corn in that heat. The L2011 study says that’s impossible, but perhaps the Texas guys and gals didn’t get the memo, they’re a cactus-tough bunch down there, hard to get hold of. Thinking on it, though, it’s more likely they got the memo and shot it full of holes for target practice. In any case, during their growing season, the Texas farmers have no less than a hundred and thirty-six degree days over 30°C, which according to the L2011 results should reduce yield by 136% 75% … which means that either I or Wolfram or the climate scientists did something wrong. I’m open to any suggestions, I’ve been wrong before.
Now, if there were to be a general warming, say a degree on average over some long time, what do you think will happen to the planting and harvesting dates in Figure 4? Do you think those farmers would keep planting at the same time of year, year after year, in the face of increasing hot days summer and decreasing yield? Do we really face a 1% drop in yield for every degree day over 30°C?
Naw … in answer to the question in the title of this post, farmers are smarter than the L2011 climate scientists. If temperatures change, the farmers change their planting times … what do you do?
My best to everyone.
w.
For those who speak English, that would be “there are other factors”. 😉
Lesson one: Farmers are not stupid!
Theory vs Reality.
Corn is grown widely in Australia though not as intensively as USA, but in our summer daytime maximum temperatures in corn growing areas rarely get below 30C. Corn still grows.
Don’t forget about irrigation. Texas has a lot of it and will play havoc with your conclusions.
You asked: “what do I do”? Well, I pay attention to the Farmers Almanac, DTN, my local co-op, the local critters, and my farmer neighbors. And I spend a lot of time outside. I don’t pay attention to know-it-all busybodies on safari in Africa.
There are different varieties of corn. So, it may be that the types of corn grown in the U.S. are different from the types grown in Africa. I know a lot of our corn is grown for livestock feed and for products like high fructose corn syrup and of course ethanol. Maybe this accounts for some of the differences in temperature sensitivity. But I am just speculating.
I’ve never known corn to bolt. But other types of cool weather plants bolt like crazy in warm weather. The problem with cool weather (or temperature loving) water-sucking plants is the habit of bolting in extended warm weather, doesn’t matter when it’s planted. An unusual run of warmth and your plants go to flower and seed overnight. Bolting pretty much kills the crop if the crop depends on harvesting intact buds and not full blown flowers.
Wonderful post. Yep, farmers are smarter. They can vary planting and harvesting times. They have a million tricks up their sleeves.
Yet again another amazing bit of detective work Willis keep it up.
Great article as always Willis. “When it gets above a certain temperature, maize growth quickly slows, and it’s worse when it’s dry”
LOL I seen a book once.
I know of only one other Willis; he is a character in a Phil Dick novel story called “Our Friends from Frolix 8”. In chapter 4 we meet Willis Gram, Council Chairman of the Extraordinary Committee For Public Safety. He too is a clever devil. 😎
Cheers!
The abstract says “Each degree day spent above 30° C [86°F] reduced the final yield by 1% under optimal rain-fed conditions…”. Later you say ” Texas farmers have no less than a hundred and thirty-six degree days over 30°C, which according to the L2011 results should reduce yield by 136% … ” It seems to me that, if each GDD30+ day equates to a 1% decrease, then shouldn’t it be, for example, 100-1%=99; 99-1%=98.01, 98.01-1%=97.03; etc. 136 repeats of this and you still have ~25 of your original 100 left. Or a total decrease of ~75%. I haven’t read the paper, so can you clarify this for me? TIA.
Herbie
I done left a werd! Novel story? Hnuk
Good catch Willis, its what is known as a aaaha moment, or as we say here in Texas an No Shit moment. I am sure if the scientist had actually talk to farmers and got some advice and instruction on the subject they would have had a different outcome. But then they would not have been published because of no AGW angle. A Farmers Almanac goes a long way to knowing when to plant what crops, i find it a big help. Look forward to your write up after you read the paper and give your anaylisis.
gee, I wonder if the continent with the most starvation might, just might have horrible soil for growing crops. Or just rotten farmers …
Excellent post.
It also highlights the perils of casual extrapolation.
The paper may have been correct about the 1% decline per day above 30 *C, but their data probably did not cover more than a 10-20% fluctuation.
They should have put limit bars on their numbers.
That said, one wonders whether the Texas farmers are getting yields comparable to those in Iowa. That might give some better sense of corns higher temperature sensitivity.
“…farmers are smarter than climate scientists..”
Duh!
Who funded the study? From what I understand NSF requires that the conclusions for the study be part of the proposal. I wonder if that, and the requirement that NSF funded studies must also show it’s “worse than we thought”, might have something to do with the results. I too could be wrong.
Could the answer be that the farmers in Texas use irrigation whereas their is no irrigation in Africa?
Maybe the math approach is wrong.
It may mean that each hot day reduces the resulting amount by 1%.
With 136 hot days, the result will be 25.75% compared with optimum conditions.
LOL, Farmer Willis!
It is good some climate scientist are cross training. I glanced at a few papers this morning. Night temperatures, lows, are an important factor in corn setting when it is in silk. You might want to send the author a neat plot of Tmin to supplement his corrigendum.
W,
I’m with you. Any amateur gardener or professional farmer knows to watch the seasons and plant when the temperatures favor the crop. As a matter, every packet of seeds tells when the optimal time for planting is in any given area of the country. It looks like this is another case of “scientists” who never leave the classroom, misinterpret data that the doers of this world have long ago figured out.
I’m thinking there must be a lot of ‘scientists’ who will sooner or later be getting a voodoo doll of you Willis. Way too much common sense and perceptive logic.
If those African examples are what you hint they are, I would guess that there must be NGOs involved, to “help” them time their planting. Maybe somebody from Ohio, or Ontario, who knows the best date to plant corn?
Anyone, this is critical. We must have more ethanol! (sarc)
Having a journal named “Nature Climate Change” – as if there were something unusual and noteworthy about climate not being static – will hang like an intellectual albatross around the neck of this once-proud journal of science.
Great exposee Willis of another ham-fisted and failed attempt to reduce a complex interaction of climate and biosphere to a simplistc back of envelope calculation.
Willis, Thanks for putting into clearer words than I can the farce this study is
I spent 2 years as a Hort Advisor in Kenya, then 2 years in the Solomons, the main concern in Kenya, is replenishing the soil to build up the water holding capacity, and nutrient retention
There isn’t a source of fertiliser in Kenya, the cattle dung is used for fuel to cook over, the forests near any reasonable village have long gone, trying to change farming practises can be and is, a lesson in futility unless you are prepared to spend time living alongside the people.
I read this study and shook my head.
Willis: Could you give a link to that US corn map? My mom lives in Cochise County, so I get over to that SE corner of Arizona frequently. I’d sure like to know where all those cornfields are.
Watch the Edwards Aquifer levels plummet in March/April as the farmers around San Antonio and Austin irrigate their crops to harvest in late May before it gets really hot.
Well, I think just saying 1*136=136% is probably a bit much, as it would have to approach asymptotically. I would think it is more likely that when temp=X and water=Y, yield=Z.
It could be worse Willis.
Under drought conditions, 136 days would see a crop of -131.2%.
Do they mean ‘one’ bad year can cost nearly two and a half years production?
Texas corn must be tougher than African corn.
Besides changing planting dates, farmers use different varieties of maize for differentes climates (i.e. different temperature and different precipitation). Heat+drought tolerant varieties are grown in hot and dry areas of the world, such as Mexico, or large swaths of South America and Eastern Africa.
Another important point is that the presumed increase in temperature over time is supposed to come from increased CO2 concentrations in the atmosphere. Now, more abundant CO2 has two effects: it may increase photosynthesis, and it may save on water, In crops of the C3 type, like wheat, the main effect is increased photosynthesis; plants get more carbon from the atmosphere, turn it into sugars and thus make more stems, more leaves, more grains. This means increased yields, usually from +20% to +50% with CO2 at 550 ppm, compared to recent measurements of 360-390 (depending on the date of the study). In C4 type crops, like maize, the effects on yields is lower, usually below 25%, but there is a very important reduction in the plant’s water requirement (about -25% to -70%). Thus in hotter and drier conditions even the same variety of maize would yield a bit more and will need less water. In addition, farmers may shift to a more heat-resistant and drought-resistant variety, if need be, and (of course) advance the planting date.
The contrary results one reads from time to time come from studies artificially simulating more temperature and less humidity while keeping all other things constant (planting date, crop variety, CO2 in the atmosphere, farming practices, and so on). This could be (possibly) adequate if you were measuring the effect of a presumed climate change on wild vegetation, but agriculture is not a natural plant-growth process: it is the result of an adaptive interaction between people and Nature; if the climate changes, both the plant and the farmer would respond.
In some extreme circumstances crops would indeed reduce yields and possibly not grown anymore (e.g. if a now-fertile zone becomes a desert), but in general we are talking about an increase of 1-3 °C per hundred years, amid large variations from year to year and from decade to decade. Time enough, and variation enough, to adapt, even if no scientist develops better maize seeds along the next hundred years (which would be very unlikely, because they do it every year).
Hello? ello, llo, lo, o… Echo, cho, ho, o… Now hitting for number 23, Manny Moto!
Willis, you are brilliant. You are smarter than 90% of official degree-carrying scientists out there I am sure. Keep your critiques coming, they are great!
I understand that from your report we have no detail of the study, but what strikes me immediately is that a fair proportion of the trial areas are in Zimbabwe. Due to the politics in Zimbabwe the country is a basket case! It has gone from being a major food exporter to chronic famine. My question is: How much of the reduction in yields is due to to Zimbabwe’s collapse and is this reduction mimiced in the other areas?
I would suspect (without any evidence) that this study shows more about the effect of political megalomania than temperature.
Credentialed, not educated. And in this case, the warmists aren’t even aware of basic, common-sense reality.
Except they probably got a lot more govt. money.
which according to the L2011 results should reduce yield by 136% … which means that either I or Wolfram or the climate scientists did something wrong. I’m open to any suggestions, I’ve been wrong before.
I think it’s called an asymptote.
Hilarious! The folks that did that study obvious didn’t think about other parts of the world where corn is grown…
Gee, hard to grow corn in Africa? Why? Fertilzer (or lack of)? Consistent irrigation (or lack of)? Farming skill (or lack of)?
Check the elevation. Some areas look to be 1km elevation. Isn’t water loss increased at lower air pressure?
Hey! No fair adapting. Or moving. You have to stand still and perish,else the rhetoric doesn’t work.
This Nature article is complete BS.
There are many species of maize/corn, some more drought or heat resistant than others.
This is like comparing apples with pears and strawberries.
You plant the species of corn/maize which is best suited for the climate in your area. That’s why there is corn/maize from Toronto in eastern Canada to northern Florida – even the goofiest alarmist should realise the difference in climate between these two areas.
And more varieties of corn/maize are appearing every year.
US farmers can likely adjust to lots of things if the government doesn’t get overly involved. And some scientists actually have to earn their salaries, such as these folks that have been working on drought-tolerant corn.
http://www.hpj.com/archives/2011/feb11/feb21/0204DroughtTolerantCornMRFE.cfm
should it decrease by (.99)^136 ?
Study region map shows what’s rigged. They mixed in lots of weather data from desert Mali/Niger/Sudan, arid Namibia and N.E South Africa for a majority of East African maize trials centered in old productive Rhodesia /Zimbabwe , narrow Malawi and recovering socialist Tanzania.
The Zimbabwe maize yields themselves are unreliable, since agricultural production has infamously suffered from a unique form of man made disaster. The study should release it’s specific data from all of Malawi, since it seems there were meteorological stations and plenty of maize plots all over that country..
A few other fcts to add …
http://varietytesting.tamu.edu/corn/2009varietytrials/cornyieldresults/GulfCoastCornHybridPerformanceTrials2009.pdf
suggests that yields in Hildago County (Edinburg TX area) are about 40-50 bushels per acre.
Yields in a prime area (Iowa http://www.extension.iastate.edu/agdm/crops/pdf/a1-14.pdf) are about 160 bushels per acre. In excellent years the yield is close to 200 bushels per acre. That looks like a ~ 75% reduction in yield due to the warm TX summers. While this is not over 100% drop, it is still in the right ballpark, especially for a locale which presumably would be an outlier in the temperature ranges used in the studies .
(By coincidence, if you treat the “1%” reduction in a “compound interest” sort of manner, the drop would be (0.99)^136 = 25% of the optimal yield. I have no idea if this is consident with the original analysis — it is just an observation).
One solitary degree day causing a 1% drop in corn yield is a number that just doesn’t sound right to me. My guess is that it’s something like per day.
During a 150 day growing season, that would give a US style measurement of 150 degree days, causing the 1% drop in yield. That may be too little response, but it sounds more reasonable to somebody (like myself) who has no farming background.
Regardless, Willis, I agree with you that farmers simply would adjust their planting and harvesting dates, so the study seems moot to me. BTW, I noticed that the study looked at tropical and sub-tropical locations, which may not be the best choice of where to grow corn.
A quick comparison shows that the corn producing regions don’t correlate with US precip maps, as long as there is a minimum amount of rainfall. The corn belt has prairie type soils combined with relatively flat ground. South of Iowa, Illinois, Indiana, and Ohio, you have very hilly terrain suitable for only small patches of farm ground.
Texas corn stops at the hill country, and same with the southeastern states. Corn also follows waterways, river bottomland.
Thanks Willis!
There is more then one county that grow corn in FL. It may just not reach ‘minor crop’ level.
http://fciig.ifas.ufl.edu/scpmap.htm
Willis: If you experiment with the Wolfram Alpha degree-day calculator, you will probably find that it calculates degree-days differently from this paper. If you set the temperature equal to 95 degF, you’ll see no day where the average temperature was over 90 degF, but there still will be 11.8 degC-days of cooling. I suspect they are calculating deg-hours above the chosen temperature (a sensible measure of the demand for cooling) and then dividing by 24 hours/day. This is not what is done in the paper, which is publicly accessible at http://iis-db.stanford.edu/pubs/23138/Lobell_2_11_NatureClimateChange.pdf
In Figure 2, did you notice that the two standard deviation error bar on the reduction in yield is the same size as the reduction in yield without drought? Could that be the reason why the authors did not include any estimate of uncertainty in their 1.0% and 1.7% reduction in yield per deg-day of excessive heat.
You are completely right, adaption is the solution. If you look at Figure 2, corn is currently being growth in Kenya, where the average temperature during the 150-day growing season is >30 degC.
Another Willis masterpiece!
How does he keep ’em coming?
Nice of nature’s tame “scientists” to act as the butt of Willis’s wry humour!
The bunch of clowns. Does someone pay ’em for this crap?
I know when I lived in Ohio (in the light green area but close to the dark green, an important factor for planting time was whether it was warm enough and dry enough to put the corn in. If not (or the farmer just ran out of time) the land was switched to soy beans (which have a shorter growing season. So if the climate gets warmer, the farmers will have an earlier start to the planting season and probably more time for the fields to dry out enough to be planted.
BTW, soil is a big factor in planting corn and the dark green areas are basically areas where there were glaciers which helped to create rich soil. The SE areas in Ohio are below the terminal moraines and thus both hilly and not having much soil.
Willis, I am having a real problem associating DD’s as I know them as they seem to be described in the article. For the heating profession, a single day may have a DD of say 6. In this case it is the average below a baseline. So if in the paper cited above, using 30*C as the baseline, one day that averaged 40*C would be considered a 10 DD. If I read the bit of abstract correctly, they are stating that growth is 1% less, per DAY that goes above that days baseline. For as your example showed, it is not hard to get 100 or 300 or whatever DD’s in a growing season. but as the temp graph below the DD graph shows, only about 20 days were actually higher in DD.
phlogiston says:
March 14, 2011 at 7:45 pm
“Having a journal named “Nature Climate Change” – as if there were something unusual and noteworthy about climate not being static – will hang like an intellectual albatross around the neck of this once-proud journal of science.”
Next up: Nature Global Rotation.
This link to the article was in Taphonomic’s comment to Anthony Watts’ earlier post on the subject. There are many comments there claiming successful corn harvests in climates just this side of Hades. {grin}
The article uses historical studies, interpolated weather, and a model that includes “ε [which] is an error term.” The studies were conducted by a number of groups and seed companies, and they tested a variety of varieties of tropical maize [n.b. – not North American] “grown or intended for farmers’ fields throughout Africa.” Possibly under conditions different from those at the test site(s)?
In other words, it seems to me that verifying this article would/will take much digging, and I hoist my glass of ice tea to those who would take it on!
I just read the Wiki entry on Maize. Apparently EVERYBODY can grow corn quite well except for that area of Africa. In fact, folks with nothin but a mud pot figured out how to cross breed and domesticate the damned stuff to the point that it hasn’t changed much over the past 2000 years. The stalk has larger than grass leaves on it, the ear of corn grows on the side, and the tassle is on the top. All this was figured out wayyyy before climate Ph.D.’s were piled higher and deeper. Thousands of years before that, it was just a piss-ant grass.
So, if folks down there can’t grow corn, something other than global warming is the cause.
Perhaps there is something amiss with the interpretation of “Each degree day spent above 30° C [86°F] “. Perhaps they are referring to, in effect, the total “cooling” degree days for the growing season offset by the “heating” degree days. That would take into account the days of cooler weather early or late in the season. In the example shown for Edinburgh, TX, the result would be a negative number, indicating that temperature did not have a negative influence on crop yield. It does not make sense, for example, that one really hot day could have a serious negative impact on yield if all the other days were optimal temperature. Also, wouldn’t the timing of the hot days also matter. A hot day early in the season likely would cause more reduction that a hot day on the day of harvest.
If the study was a simplistic as it sounds, it was simply a waste of time for everyone as no meaningful information resulted, except of course to fuel climate lunacy.
In the blog, I read the original Nature peice – Gosh!
Next, I read Willis’s observations – Ungosh!
And all sorts of questions, which must be answered urgently, arise in the mind of this (ex) relatively uneducated bureacrat, now hypothetically charged with the duty of making financially significant decisions on all sorts of subjects about which I know next to nothing:
(1) Who is right? (Must be the original article – after all it was in a respected publication. )
(2) Why does Willis not publish a comment or something in Nature? Who is he, anyway? Do people with power/influence agree with him?
(3) What do I tell my minister, who takes decisions on on all sorts of matters he knows nothing about as a matter of routine, on the related question of subsidies to windmills?
Enough!
It will take more than blogs to bring the body politic to its senses. Friends have got to be made in the right places. And then what sort of contortions are we going to have to come up with to preserve the dignity of our politicians, who, after all, only did what we told them?
And I do like Willis’s writing, although, in my experience in places similar to that of which he writes, the winds blow into an appraching storm, not out. Have his efforts been assembled into a book somewhere?
Obviously corn is not a major crop in Mexico.
Remember the remark, “the scandal in Washington isn’t what’s illegal but what’s legal”? What’s scandalous here isn’t this flawed (// “illegal”) paper, but that it passed peer review (// “legal”).
Growth is less when it’s warmer? Might this affect some tree ring studies?
Ken Stewart says:
March 14, 2011 at 6:54 pm
Ken, remember this is average daily temperature (max + min)/2, not maximum temperature. Run the Wolfram Alpha calculator for a town in the growing region.
w.
PS: I.e., the reviewers should have brought up the objections that have been brought up here and in the earlier thread on this paper. Why didn’t they? Because that would have hurt the cause, because they would have been criticized by more extreme alarmists for their stance, and/or because they believe that “any stick will do to beat the devil.”
Herbie says:
March 14, 2011 at 7:17 pm
Possible, but I don’t read it that way. It would be difficult for the L2011 folks to calculate if that were the case. I read it as a linear trend. Makes no difference to the conclusion either way, though.
w.
Using 30°C as an upper bound is just wrong. Sweet corn (maize) likes it hot, and grows best between 85°F and 100°F, or 30°C to 38°C. Above that range (and below it) maize doesn’t do as well, but some varieties of maize have been grown in equatorial South America for thousands of years. Maize pollen has been found in terra preta (Amazon dark earths).
This book is a good read on corn agriculture in Africa:
“Maize and Grace: Africa’s Encounter with a New World Crop”
http://www.amazon.com/Maize-Grace-Africas-Encounter-1500-2000/dp/0674025571/ref=sr_1_1?ie=UTF8&s=books&qid=1300166132&sr=1-1
I agreed with Anthony’s previous post, that the Eurekalert description of the study was crap.
I managed to find the published report on line and posted a link to it in a previous post without a “subscription”.
With all due respect, Willis, I think you’re being harsh on the authors of this paper.
Somehow I find these discussions of similarities of growing corn in temperate (non-tropical) regions with equatorial (tropical) Africa a bit disingenuous. Why? Because it doesn’t really get cold at night in Africa like it does in Texas or Illinois. You don’t get seasons in Africa like you do in Texas or Illinois. They are discussing agriculture in an entirely different climatic regime; one that is not a prime location for corn growth.
Maybe they shouldn’t have linked the potential results to possible global warming. But given the contributions that Norman Borlaug and CIMMYT have made to civilization, I find it difficult to fault them for this paper. Without Borlaug and CIMMYT we would probably have worldwide starvation. Don’t believe me? Fine.
Google Norman Borlaug. He’s someone that most people have never heard of but has impacted humanity incredibly, and who deserved his Nobel prize
I suspect you’ll find that map corresponds more to where the tall grass prairie used to be. It is likely a matter of soils, as well as summer climate during the relatively short growing season.
Corn/maize was genetically-modified from the grass teosinte by the Maya and developed by other native peoples in north and south America for thousands of years. It is a tropical grass, and grows in tropical conditions. Iowa in the summer is tropical, thanks in part to the corn which generates its own microclimate in those conditions.
You listen to the farmers when it takes down global warming, but commentators ignore, insult or accuse them when it comes to ground-truthing ethanol production, crop prices, the very nature of agriculture, or the wind turbines on the horizon.
That is not a sign of the sort of truth-seeking one would desire in a site such as this.
Actually, I think the corn is smarter than the L2011 climate scientists
Having spent many years living in Swaziland I can contribute the following about maize production there:
Maize yield is highly dependent on 1) the seed variety chosen, often a hybrid of recent regional development, carefully selected with professional advice; 2) the planting density per ha which is a guesstimate on the coming rainfall (which varies in a sine wave fashion over a 19 year period, presently very wet); 3) the timing of the first rains and the development of weeds by the time schools close (‘weeds’, many of which are edible have a very large effect on yield); 4) the relative proximity of school closing for the year: if planting is late, it may be at 3-leaf stage when weeding (hoeing) starts after kids get out of school. In that case yields will be highest. If the planting is early and it is well past the 3-leaf stage when schools close and weeding starts, yields plummet.
Heat? It’s Africa man, nearly as hot as Atlanta in July! Well, almost…
Most vegetables stop growing between 10h00-16h00 when the temperture goes over a threshhold. That is why shade cloth promotes growth all day.
Short season maize is grown in the Kalahari Desert and the southern Swazi lowveld on dry land: very dry, very hot. According to the Malkerns Research Station’s experts, the easiest way to increase yields of maize is to plant early and move the end of the school year forward.
The paper’s underlying bedrock? From here it looks like statistics, all the way down.
juanslayton says:
March 14, 2011 at 7:47 pm
It’s from here (PDF). Per google earth, it’s likely some of the center-pivot watered stuff north of Pearce and around Elfrida.
w.
“I’ve never known corn to bolt. But other types of cool weather plants bolt like crazy in warm weather. ”
This study finds that plants have a temperature gene and will respond to high temperatures to protect the next generation of seed.
http://ec.europa.eu/research/headlines/news/article_10_01_21_en.html
In a nutshell, the real scandal isn’t that this paper got written, it’s that it got published.
“There isn’t a source of fertiliser in Kenya, the cattle dung is used for fuel to cook over, the forests near any reasonable village have long gone, trying to change farming practises can be and is, a lesson in futility unless you are prepared to spend time living alongside the people.”
Too bad they don’t have some low cost coal for their fires. That would have saved the forest and allowed them to use the dung as fertilizer. No hope of that in the future once the UN and IPCC get done with them.
The Economist issue of February 26th 2011 has a series of articles “A special report on feeding the world” which might be of related interest if you can ignore the AGW will make it worse slant.
http://www.economist.com/printedition/index.cfm?d=20110226
I can tell you that there’s some corn farming here around the Phoenix area, probably not enough to be counted on the map. I have watched some farms get 2 crops in a year out. I’m not sure when they plant, but they’ll be harvesting in July, and then another crop will be sprouting up and gets harvested probably in October (temperature is still in the upper 90s in October).
Lots of people referring to wiki in here.
Dear Willis,
Your question, “which group is smarter”, brings up clearly the problem with the present generation of “scientists”. It has become too easy to become a “scientist”. It is still very hard to make a profit as a farmer.
The question should be: “which group works the hardest” .
In a blog of questions and answers in physics, a young fellow asked : What are the easiest fields in physics to work on? Not so easy that they have been solved centuries ago or elementary textbook stuff. Something you can actually work on, but easy enough to take minimal effort.
Note the “minimal effort”. It is the science aspect of the “me” generations we have managed to bring forth to the world: the maximum gain for the minimum input of effort.
Thirty years ago, I had been shocked when giving a lecture to prospective graduate student applicants one of them asked : “what is the career path and what type of pension will we get?”. I was shocked because my generation of physicists, just coming out of the hardships of WWII and a civil war were happy to be able to play and discover in physics, and did not give a dime about “job security” at that age. This fellow got his PhD and has been a very hard worker.
Counting 15 years for a generation, two generations later we get this minimal approach, the Spock generation of permissive up bringing? In combination with the needs of academia to grow and create tenure posts, levels of examinations have dropped and the science system is being filled with minimal effort candidates for study, who should have been rejected at the word go. Minimal effort does not give large grades.
So enviromentalism and stuff are the right place for these minimal effort fellows and according to ” work expands to fill the time available” , “nonsense expands to fill the journals available”. Journals make a living too.
Sadly.
Maybe the Dingo at their corn?
Mexico grows corn in winter…
http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=49652&src=eorss-nh
I see that many samples were taken in Zimbabwe. Remember that when it was called Rhodesia, it was referred to as the breadbasket of Africa. I guess the political situation, murder of farmers and theft of farms hasn’t affected the results of the tests here?
Based on IPCC “greenhouse” scenarios, tropics should not warm but mid to high latitudes should. So all that screaming about Africa is off.
Tim Folkerts says:
March 14, 2011 at 8:17 pm
Thanks, Tim. However, the temperature during the growing season is similar across Texas (due to the delayed planting and harvesting). So production should be down all across Texas.
In addition, here’s a study of field trials of corn in Hidalgo County, Texas. It gives average yields of 160 bushels/acre, with some hybrids giving 180. Texas-wide average is lower, at about 120 bushels/hectare.
So even with all of the adjustments, the numbers still don’t work. Texas yields on average are three-quarters of the Iowa yields. In addition, the Iowa farmlands are much richer, deep topsoil.
w.
PS – I finally unravelled the actual relationship they discuss. They say that the natural log of the yield is linear with the GDD30+. So yes, the yield should be down to a quarter of the original yield … still doesn’t make the numbers work, though.
From being an organic gardener in Kansas I find the best tasting and most drought resistant growth comes out of soil with loose texture and lots of organic matter, the absorption rate of water out of the soil, is the make or break criteria for dry land farmers. The finer and clay like the soil with less organic matter content the corn is grown in, determines that it is the first to dry up and die when it get windy and dry.
You can drive through the country and look at the condition of the corn crop in drought periods. Most of the local farmers keep an eye out for the fields that consistently survive, when planning more land purchases. Milo is the back up crop for dry areas and years, still pig and cattle feed.
The dirt in the photo from the article Anthony links to, probably wouldn’t grow decent grass for pasture, until a decent sod was established.
So, do people actually get paid for writing a report that can be demolished in one fell swoop by a few google searches? OK, W has a brain which for sure is by far larger than mine, and he also makes demolishing the report look so easy.
One question: Can we have our money back please?
Next question: How many ‘scientists’ have been paid and are being paid for producing ‘peer’ reviewed ‘scientific’ reports that can be ‘Eschenbached’ in a few minutes?
Taphonomic says:
March 14, 2011 at 9:22 pm
Southern Texas is at 26 North. The bulk of the study sites are around 20 South. Neither one strikes me as particularly tropical. And yes, it gets damn cold at night in southern Africa.
w.
The biggest problem with high temperatures and growing corn are when the peak temperatures occur during pollination. This is about a 3 to 5 day period and high temperatures will cause low kernal count on the ear. Growers mitigate this by planting the correct hybred early enough that pollination occurs before the peak summer temperatures. If there is adaquate moisture (in the ground) corn loves the heat.
Taphonomic says:
“Somehow I find these discussions of similarities of growing corn in temperate (non-tropical) regions with equatorial (tropical) Africa a bit disingenuous. Why? Because it doesn’t really get cold at night in Africa like it does in Texas or Illinois. You don’t get seasons in Africa like you do in Texas or Illinois. They are discussing agriculture in an entirely different climatic regime; one that is not a prime location for corn growth. ”
Actually nearly all the growing sites in Africa are in highland areas where nights are fairly cool. The sites in Lesotho for example are in an area with regular frost in winter.
[Snip . . Off topic . . ]
The soil in African is rich in Laterites: iron and aluminum oxides. As shown here:
http://www.britannica.com/facts/5/418439/laterite-as-discussed-in-Africa
Which is why the soil is red/brown. Aluminum stunts the growth of plant roots, which is why Monsanto is creating a GMO variety of corn that is Aluminum resistant.
Maize is not native to Africa, which has a highly acidic soil, hence the presence of Laterite.
http://pcp.oxfordjournals.org/content/36/1/201.full.pdf
http://www.ehow.com/info_8034957_aluminum-toxicity-soil-acidity.html
I don’t understand why these “temperature”researchers can’t do just a bit of homework. The temperature, of course, has everything to do with why tropical jungles are so desolate….oh, wait…jk
And on the other hand, if global temperatures were to rise and, as it is reported, it were to warm more nearer to the poles and less nearer to the tropics, would there a net overall greater or lesser opportunity for good farmers to increase global corn yields and yields of other crops? As surely some significant areas are currently too cold to produce corn economically.
When I plant seeds for my garden I look at what the weather is and has been doing so I know if it worth while doing it or should I delay.
James Bull.
I agree Willis. In the lowveld, Swaziland (one of the study countries) reaches -4 at night. Much colder than the higher areas like Manzini, strangely enough, where it never gets a frost. Swaziland is at 26 South. Same as Texas.[shome mishtake shurely]
Glad you got the math right. 1% drop from the last value. The 1% is clearly untrue save perhaps for a small numbers of days and that is likely to be highly dependent on the seed variety. Humidity will also play a major role. I expect the real relationship to be related to the humidex, not the temperature, and to be limited in range.
Just to the south of Swaziland in the KwaZulu-Natal highlands the farmers have ‘ton clubs’. The ten ton club has members who have cropped 10 tons per hectare. There is a 12 ton club and so on. There is no economic return above 8 – they just do it for fun.
Ox-drawn commercial farmers in Swaziland (yes, they exist) get about 3 t/ha and ‘rented tractor’ ones get about 4.2 t/ha. Those are old figures. They reflect ‘peasant farming’ with hybrids and fertiliser. Rain appears to me far more important than temperature: i.e. check for timely rains, not +30 days, especially around tasseling.
And further – about 50% of all the food grown in Africa is eaten by pests. Think about how easy it would be to offset cold or heat or drought of flood-related losses with well known control measures.
Did anyone do a study on the effects of cold on yields?
Perhaps this wouldn’t get published by Nature.
Jeff Alberts says:
2. Corn is only a minor crop in many regions within that general preferred temperature band. So obviously, there’s other factors.
For those who speak English, that would be “there are other factors”. 😉
Well, to quote my Texas Uncle:
“Well, son, we won’t go holten that ‘gainst yah. There’s been lotsa facturs ’roundt hearsabouts, and spiiken Anglish aint won we been known for holten ‘gainst a fella.”
Soes if yous ‘ill just stop t’ holler ‘n about it, we ken prolly get you’all ‘t pass with’n out too much trouble….
‘Corse, if you’all are gonna make a fuss ’bout it, well, let me introodoose you to some Texas “Culturall Art E Facts”… This ‘un here, it’s calt a “Three Fifty Sev’n Magnum” and this other ‘un, it’s calt a “Foorty Five Colt”…
😉
I “married in” to a Texas Family. It has been ‘interesting’….
They would do ANYTHING for me and my wife. On the other hand, in the “meet and greet” of the family my Texas Uncle said “Howdy. I want to welcomes you to tha familly. And just soes you know, if you EVAH do ANYTHIN to hurt this lttle girl, I’m gonna personally hunt you down and kill you.” Delivered with a sincere smile… Now, I grew up in a ‘western town’ so I was not totally unprepared… but he WAS a guard at a state prison …. and always traveled armed… I said: “Aint nobody evah gonna hurt my wife. But thank you for your concern” or something close. Basically, the other side of The Deal “She’s mine, and I’ll die before I let someone hurt her; but if you are near it’s nice to know you will help with the shooting”.
The simple fact is that he was NOT kidding. This is the “code of the west”, and I knew it. It was his Honor Duty to inform me that he was “on the job”. Just as it was my duty to inform him that anyone who so much as touched a hair on my new wife was going to be skinned, but I was not sure if I ought to do it before, or after, he was departed from this world…. so could he help me out with that bit of stupidity on my part and ‘splain it to me…
Now, the hard bit for folks “not of the ken” to get: I’m well above average IQ, and so is he. There is a tendency to attribute to intelect that which is best assigned to cultural norms…. Well, “It ain’t that…”
The point?
I’d suggest, just a tiny little thing, that maybe you ‘oughten not t’ be crisizisin a cowboy ’bout how’s he’s speakin’… ’cause … well… I’m married to a Texas Gal an he’s a cowboy an well, there’s this here “Code Of The West” an it can be bit tricky for you’all folks from Angland t’cotton to it an all… and I’d really rather not have to ….
Willis, another beaut! I spent a number of my early years after leaving high school working on and near agricultural and horticultural research stations of various sizes. A weather station, no matter how basic, was always part of every station. Most agronomists know that weather is incredibly local and doing nifty staistical extrapawhosis never provides real and useable data; without factual weather data the research is pointless. The soils and the nutrients that crops are grown in are important too, but any real study of the this seem largely absent in this paper. I fail to see any real point of the paper; the agronomists I knew all those years ago, who were generally weatherbeaten from actual outdoor observational work, would be horrified that scientific study in their feild can be largely carried out in a comfortable office sitting in front of a computer.
Richard
March 14 2911 08.04
You Sir have hit the proverbial nail,
Having been born into a corn growing family, and also traveled,’there and back in Africa’
Corn is a fantastic plant, the seeds are set in the cob the in same direction as they form on the stem, you will find that in a field of corn that the best yield is always in the outside of the field, this is because it gets more sunlight, and if the seeds are planted in the right direction so as the cob is on the outside of the row the yield will be greater all over the crop
Good post, certainly if Framers were not smarter than some scientists then we would be very hungry.
Keep em coming!
I’m late of course, but did someone spend a lot os hard-pressed taxpayers’ dosh on arriving at a conclusion that farmers, as wonderful as they are, complain that it’s too hot??? I thought they complained because it was too hot/cold/wet/dry/wrong type of rain/wrong kind of heat/wrong kind of cold, for too long, etc, basically everything & anything! I blame all that nuclear testing in the 40s & 50s that’s caused all that evil CO2 to be emitted causing catastrophic global warming/cooling/no difference/slight difference/possibly some difference but we can’t be sure difference……..I quit! Watch out for the anti-nukes surge in the coming weeks & months. Sarc off. :-~)
etudiant says: Excellent post. […] That said, one wonders whether the Texas farmers are getting yields comparable to those in Iowa. That might give some better sense of corns higher temperature sensitivity.
all this is on line from ag schools and ag extensions. You vary the variety or the planting date as needed. This is just “below basic” stuff. Corn cuts off at 50 F low and grows best at 86 F so above that is pretty much static high (remembr it’s only peak for a few minutes a day…)
See:
http://www.ag.ndsu.edu/pubs/plantsci/rowcrops/a834w.htm
Corn is currently grown in every county in the state, though the productivity and risk of production varies considerably from region to region. Temperature, rainfall and radiation are the major environmental factors that influence the growth and yield of corn.
Yes, “radiation”. Did they measure that?…
It’s a temperate crop. So if it get too hot, they will swap to soya beans… FWIW near the part of Texas where I spend “some time” they also grow sorghum, but only in those places where they have some issue with corn. The point? You change horses when the one that can’t take the heat keels over…
More warm and longer warm is better. I think some academic screwed the pooch…
There are many ways to calculate heat units. Usually the upper and lower bounds are set by the particular plant of interest. This says corn needs AT LEAST 50 F but tops out at 86 F (though will grow hotter, does not get more gain). So for every place that rises above 86, somewhere else rises above 50 F…
So it’s well established that 86 is the top growth rate (over about 120 F you need to ‘go negative’ on the factor instead of just pegging at high growth) and that’s just not a problem, really. As long as you REACH 86 F you can reach max growth…
So how much of the planet is below 86 F and could use a bit more warmth?…
Richard says:
March 14, 2011 at 8.04pm
‘I would suspect (without any evidence) that this study shows more about the effect of political megalomania than temperature.’
Sounds like climate science and agw in general, more about political megalomania than temperature.
I was born in a small SE Minnesota town right on the edge of the dark green portion of the corn map and have spent most of my over six decades of life here. My wife of nearly three decades was born in S. Central Iowa and her mother still lives there. As a consequence I have spent good deal of time over the last thirty years driving the back roads through some of the most productive corn growing areas on the planet. It is entirely usual for corn fields to have completely different results when the only thing that separated them was the road I was driving, or sometimes a fence row, or even in fields planted by the same farmer based on drainage differences. It is commonplace to see test plots planted with several rows each of a large number of different seed varieties where the variable results are obvious even from a passing car. Corn yields are the product of a wide assortment of variables. Even if they had a recording thermometer attached to every other cornstalk it would only enable them to suggest a possible correlation between temperatures and corn yields, unless all the other variables were adequately accounted for. Trying to claim a causal relationship based on temps interpolated across vast distances with almost no data on the other conditions affecting yield is just laughable.
Pitstops tend to be fairly widely spaced across central Iowa, so I’ve had the opportunity to venture into cornfields to conduct personal drainage checks on quite a few occasions. I couldn’t unequivocally deny that high temps might decrease yield, but I can report that on +90F days with little breeze, if you stand fairly still in an Iowa corn field you can actually hear the stuff growing.
EM: Great contributions.
BTW, someone in another comment mentioned the old rule of thumb that corn needed to be “knee high by the Fourth of July” to insure a good crop. I’m afraid that has become obsolete. Nowadays it’s more like “head high by the Fourth of July”, unless your a hot prospect for a low post spot in the NBA.
My family farmed maize, cattle and sheep in the Free State Region of South Africa from around 1860 – 1930, one of the regions selected for the paper under discussion. The area is typical ‘steppe’ country, rising to mountains in the East (The Malutis and the Drakensberg) which intercepts any potential rainfall coming from the Indian Ocean. The Free State Plateau is 4,000 feet above sea level on average, rising to around 5,000 feet in the East and the foothills of the Malutis. It’s pretty dry country folks and the soil, though good, cannot give the sorts of yields enjoyed in countries like the US, Canada or the European and Russian equivalent areas.
Having lived there myself I can say that most of the summer is hot, typically above 30°C and most of the rain is from thunder storms that sweep across from the Atlantic side of the continent. Winter snow on the Maultis and the Drakensberg provides most of the feed water for the major rivers round there.
Why did my family cease farming? We were finally wiped out by the South African equivalent of the 1930’s ‘Dust Bowl’ years. the drought lasted a good five years in the Eastern Free State and destroyed crops and grazing. Entire herds of cattle died being moved in the hope of finding water near the coasts – some 200 – 300 miles at the minimum. No rain for about five years followed on from an infestation of ‘Rinderpest’ a disease carried by wild animals, but fatal to domestic stock. It bankrupted most farmers, including my Great Grandparents, and drove them off the land. This sort of heat and drought is very much a cycle there, probably operating on around a 100 year switch round.
Yes, heat in these areas affects growth – but the lack of water when it gets very hot affects it even more. The mines have been pumping out the ground water for a century or more and the water table has dropped by something of the order of 1,000 feet. The desert to the west, the Kalahari, is encroaching by about 20 miles a year at present, though the closure of some of the deep mines may allow the water table to recover.
To me this paper is a classic case of Expectation Bias and Tunnel Vision. Crops reducing? Must be Global Warming. What d’ya mean there are other factors?
Willis,
The more likely suspect in Africa is poor growing practices.
I also believe that African countries, if I recall correctly, have rejected GM crops that are designed to withstand heat, among other things, better.
By the way, 1% day per yield reduction results in an asymptotic function., not a linear drop.
Willis, I would bet the difference in Texas yields is RH%. I grew up in Indiana. We had corn everywhere, used to eat feed corn right off the stalk, uncooked. But my observation is that it loves humidity. If one shifts the growing season in lower latitudes, the shorter LOD will produce lower yields than the standard season in higher latitudes, with nutrient and water being equal.
Dave Wendt says:
March 15, 2011 at 1:57 am
I’ve never seen corn head high here in New Hampshire by the 4th. We’re lucky to get knee high. Not surprising given the latitude and the 14″ of snow on the ground (somewhere around 35 cm).
Of course, the map Willis included says we don’t have corn here, so perhaps that crop that grows in floodplains where it’s flat enough for tractors isn’t really corn. Sure is good though come August and September. Looks like grass. Maybe it’s bamboo.
Then again, up heah our best known crop is rocks – we don’t call ourselves the Granite State fer nuttin’. We’re so desperate for crops we boil down tree sap and put it on hotcakes. (Which global warming says we won’t be doing in the future. Some friends were up most of the night boiling down 1,000 gallons a couple days ago.)
As for that graph on which we’re abusing “the limits to growth,” Willis said it was really linear with the log of GDD30+. I was going to suggest the yield curve likely starts out flat, steepens and then tails off as the last areas to give have more than average water and shade. They wouldn’t do well, but do better than a brown corn stalk sticking out from dust.
“2. Corn is only a minor crop in many regions within that general preferred temperature band. So obviously, there’s other factors. The usual suspect would be water, second would be soil.”
Water and soil aren’t generally chronic problems in the corn belt. Terrain is likely the biggest determinant outside climate. Cornfields are usually on vast flatlands. Other crops with higher value/acre can be economically cultivated on terraced land but commodity staple crops that rely on being able to pull big wide attachments behind a tractor can’t compete when grown on more challenging terrain.
One thing is for sure from the map… corn grows best in temperate climates with reliable but not excessive rainfall. I see it growing in South Central Texas but it usually doesn’t look as good as it did where I grew up in Western New York State. When I lived in Southern California usually the only place you saw it was in hobby gardens not farm scale production. In SoCal you couldn’t swing a dead cat without hitting an orange grove, avocado grove, or strawberry field.
The study period almost exactly matches the politically inspired economic decline in Zimbabwe that started in late 1998 culminating in the progressive eviction of 90% of commercial farmers from their farms. The hyper inflation that followed impacted through the economy affecting power generation (essential for irrigation), fertilizer production and distribution, availability of foreign exchange vital for spare parts and all the extension programs and crop development activities that were sustained by productive farms and seed development programs.
Compare and contrast with Zambia that is recording record harvests and productivity levels. http://hken.ibtimes.com/articles/113728/20110217/zambia-2011-maize-output-seen-beyond-2-8-mln-t.htm through improved extension and farmer education services (and a few ex-Zimbabwean farmers). Amazing what can be achieved despite the alleged impact of climate change.
Further to that it is obvious that the Zimbabwe corn/maize crop is totally dependent on rainfall. This season started out well but there was ( another ) prolonged mid-season dry spell that has ruined the crop in the Masvingo, Manicaland and Midlands provinces.
This is because of the destruction of irrigation schemes by untrained farmers and others who simply cannibalized the existing infrastructure for sale as scrap because something given for free has no value. The primary reason for that statement is that the land is not owned by the farmer. He has no legally defensible title as he is there on a “grace and favor” basis by government. This means that the farmer is unable to raise loans against the land as it has no sale value. He cannot pledge, sell or bequeath the farm.
It is true that high temperatures cause wilting in Zimbabwe because the high temperatures come about because of the absence of rain , think cloud cover. Irrigated maize is highly productive and yields of 10 t/Ha are not uncommon on those farms that irrigate. Whilst hybrid seeds are used in Zimbabwe GM seeds are banned and as was mentioned there are severe constraints on the supply of fertilizer because of massive contractions in the economy.
Zimbabwe needs about 2m tonnes of Maize a year to meet domestic demand. This has not been achieved in the 10 years of the land revolution and has been on several occasions less than 1m tonnes. The crop is almost totally at the whim of the rainfall and despite there being several technologies available to limit this dependency they are not applied because of lack of capital ( valueless land ) and government policy on land allocation and GM crops.
My grandma had an Indian woman from the Nez Perce tribe for a nanny when she was young. That woman could grow just about anything under any conditions. It was from her that Grandma learned about the corn hill. At the bottom of each hole in the dirt mound (IE hill), she placed a fish, covered the fish with a bit of soil, then planted the corn. Pole bean seed was interspersed with the corn seed, and squash was planted on the outside edge of the group of corn and bean seeds. The only other thing we did after that was remove suckers from around the hill of corn shoots so that only 3 or maybe 4 stalks grow in each hill. The soil nutrients were helped by the bean plants and the squash plants kept the soil cool, moist, and free of weeds.
One year she decided to put chicken droppings instead of fish in each hill. Ever watch that move, “Little Shop of Horrors”? We still don’t, to this day, know what that crop was, but we stayed out of the garden at night.
Another half arsed paper to bolster the ‘consensus’ in the next IPCC report.. Thanks for the analysis Willis! I get the feeling you’ve only hit the tip of the iceberg with the inconsistency and data mangling used to trot out the same old predetermined conclusion in this one and I hope you have time to keep digging..
There’s another—indeed a legendary—Willis in Robert A. Heinlein’s classic, Red Planet. He’s a Bouncer, an amazing mimic, and as it turns out, a Martian young’un.
/Mr Lynn
“gee, I wonder if the continent with the most starvation might, just might have horrible soil for growing crops. Or just rotten farmers …”
Seriously, Africa has good land and FABULOUS resources: Rhodesia exported food by the ship loads, Zimbabwe – the same country – imports it …when it’s not too poor to just starve.
And, truth be told their farmers aren’t stupid, but they live in a society where the concept of “peace, order, good government and freedom” in the pre-1950 Western terms are concepts that are culturally alien, and highly discouraged by their ruling class.
It’s hard to get ahead when you are systematically ground down.
One of the references in this paper is to a study in the US which yielded similar results.
Nonlinear temperature effects indicate severe damages to U.S. crop yields under climate change
http://www.pnas.org/content/106/37/15594.full
The discussion includes the following:
While looking for information on “normal” year to year variability and causes of such variability in corn yields, I ran across the following:
Trends and Variability in U.S. Corn Yields Over the Twentieth Century
http://www.sage.wisc.edu/pubs/articles/F-L/Kucharik/Kuch2005EarthInt.pdf
All would agree that there is some temperature above which yields would suffer and based on current technologies and practices there is some maximum yield. These studies indicate that the limiting (ideal?) temperature is somewhere around 30 degrees C. We can discuss the rate of decline at higher temperatures and it surely is impacted by other climate variables and grower practices. In any case, improved varieties will likely make corn more heat tolerant.
Willis, almost everything about this is wrong.
Even the US corn production map.
Extreme South Florida, Miami Dade County, has over 40,000 acres of corn in production every year. With around 15,000 acres of sweet corn.
South Florida produces around 80% of the countries domestic winter produce.
They would never be able to figure out the degree days for South Florida this way, because they are not smart enough to figure out we plant and grow in the winter.
We grew a patch of sweetcorn in the side yard here in eastern Massachusetts. Came in well for a couple of years, until the raccoons found it. They would grab the ears just before they ripened enough to pick. So we gave up.
Obviously I have nothing of substance to contribute to this interesting thread, other than wondering (as usual) what it would take to get the authors of this pretentious (or is it pretend-science?) journal to come here and defend themselves against Williservation (that’s portmanteau for Willis-eviseration).
So I’ll let Travis Tritt sing mournfully about. . .
/Mr Lynn
“…and it’s worse when it’s dry.”
They really meant it when they said this ‘wasn’t rocket science’……..
The problem with this kind of science, is not in the actual data compilations, but in the sweeping conclusions that are being made, superbly highlighted by Willis in this instance of a 136% decline in yield.
What they have attempted to do, is to observe corn yields and max/min temperature readings and produce a correlation between the yields and degree days. They then take this correlation, having ignored a myriad other factors, such as precipitation, pestilence, strain of corn, fertilizer concentrations, irrigation levels and human inputs, then having apparently disregarded the probability that the correlation arose by chance, and from that formulated a ‘general law’ of corn production, namely the 30 degree day law.
Maybe the actual paper is a bit more cautious than this, but that is the impression being conveyed, and I’ve no doubt that is how it will be portrayed by certain media outlets.
Soil is a big factor. In the midwest the soil is great and corn is the most perfect green 8 feet tall stuff you could wish for. In the south the soil is cr*p and it the corn looks deprived. Corn is a C4 plant and it is very hard to make it too hot for it. I would bet they are confounding water stress–at higher temps the corn is running out of water. But under global warming rain is supposed to increase. Idiots.
“Brazil’s largest summer corn producing states are Parana, Minas Gerais, and Rio Grande do Sul, which account for approximately 17, 14, and 11 percent, respectively, of the total corn crop. Parana also produces a sizable winter corn crop which accounts for nearly 8 percent of the total corn produced in Brazil; winter and summer corn together in Parana account for 22 percent of Brazil’s total corn crop, making Parana the largest corn producing state. The largest winter corn state is Mato Grosso, which plants winter corn after soybeans in a common rotation, comprising approximately 8 percent of Brazil’s total corn production.”
For Parana:
NOAA Station Id: BZ83231
Latitude: 12°33’S
Longitude: 047°50’W
Elevation: 275m, 902′
All of the mean monthly day time temperatures all year are above 86 degrees for Parana.
jan dec avg
87.8 87.3 88.2 89.2 89.4 89.6 90.3 93.9 95.4 91.9 88 87.1 89.8
I would consider the effects of irrigation. Irrigation would lower the temperature in the corn field. The calculated GDD30+ based on the weather station would not be the same as the actual GDD30+ at the field site.
Looking at figure one, and specifically at Zimbabwe, those two circles down at four o’clock represent Triangle Estate and Chiredzi which are down in the lowveld. Up until the beginning of the ‘sixties and the establishment of the Sabi (now Save) River Scheme, the growing of maize, or almost anything else useful in that area, was pretty well impossible because of the heat and the low rainfall. The heat results from the altitude of around 1500 feet, which at about 31 degrees from the equator is not to be sneezed at. The area was transformed with the coming of the Sabi Dam, to, arguably, the most productive land on the continent. Mostly it was sugar cane and fruit, with maize and winter wheat very much of a secondary consideration.
What changed was the availability of water. The heat has not changed in the intervening fifty years.
The three larger circles on the map, much more important for maize production, are along the central watershed and are broadly at 4000 feet and upwards. There the rainfall is higher and somewhat more dependable, but again there is not a great deal of it that is not irrigated. (I speak from a time warp. How much of that farmland is still in production, or has the electricity supply for irrigation I am not sure, but if the power goes off in the lowveld the whole area will revert to bush within a year or two).
I can’t wait for these scientists’ next work to try to tell winemakers where they can and cannot grow a good grape.
If you’ve never sat and talked with a winemaker, I recommend it. Good ones can coax flavor from the seemingly crappiest sand imaginable, in climates the seed is not good for. Many of them have very little science background, if any. Growing things is more art than science.
My apologies for the mistype above. Zimbabwe’s lowveld is about 21 degrees from the equator.
The dec and avg were supposed to be over the last two numbers. I lost the spaces.
I grew up around the Phoenix Metro area of Arizona (BTW could be in the 90s in some areas this week). Some of my friends where Oodham and lived on the Salt River Indian reservation. Some of the families grew corn quite successfully. Amaizeing, you’d have thought that they had been doing it for generations.
BTW, Its the Marxists and their buddies that are the real cause of the problems with African agriculture. Its hard to grow crops when you are running for your life, plus our humanitarian grain shipments that undermine the financial viability of the agricultural industry does not help much.
There is an amazing array of information here contributed for free from a diverse set of commentators. My bottom-line take-away? The poor academics…with their constipated methods…ain’t got anyplace to hide. I almost feel sorry for them.
Pamela Gray? I love your little tale. Willis? You are a force of nature. I love this stuff.
Saw an article in the Minneapolis Star Tribune yesterday, aka The Red Star so it’s hardly a right wing organ.
It concerns the perfectly laudable effort by Episcoplains to send Mosquito nets to Africa to help save some of the 1 million or so people annually, mostly children, who die from Malaria there.
Their solution is nets, people get bitten and infected when they sleep indoors. But the size of the problem is actually a direct off shoot of the blanket ban on DDT which prohibits indoor as well as outdoor spraying. Which shows just how devastating the unchecked green movement can be.
But hey come to think of it a million here and a million there and pretty soon you’re talking real people aren’t you ?
http://www.startribune.com/lifestyle/faith/117910349.html
Hi Keith and yes what you say is true as I am an ex-Rhodesian myself.
What I find amusing is that the location of the crop trials are mostly in inhospitable and unsuitable cropping areas or areas where record keeping is certainly unreliable at best. Zimbabwe in particular is a very strange choice for the bulk of the tests because of the problems outlined in Keith’s post, the scarcity of fertilizer, suitable seed and the collapse of the irrigation systems/organised farming.
Using Google Earth to peek at some of the marked areas is useful including the maize hydroponics establishment in the middle of Lake Victoria.
Its bad to be wrong but it evidently won’t stop grant money.
They could learn a lot talking to successful farmers. Who is it best to ask, if they wanted first hand knowledge about anything. Normally the people closest to what you wanted to know would be a good place to start. It seems like a good idea to have some up front first hand knowledge about the research before starting. A good place to start is with people who are successful and then talk to those who are not. Or the other way around, which ever is your style. You just might have a better idea of what to look for in the research and avoid as much as possible mistakes. And it is still bad to be wrong.
In drought conditions, there is research showing low level soil biota corn crops do badly in comparison to soils with a healthy thriving soil biota.
http://soildoctor.org/?p=310
I tried growing corn just outside of Seattle. It was a waste of time.
Managed to get 3 or 4 baby corns per plant.
90% humidity is good, 100% humidity(precipitation) is bad.
This “peer reviewed” study is the perfect example of the decline in climate science, or more accurately, the decline in science we’ve seen due to the corruption now evident in a large segment of the scientific community. Other factors that would cause a reduction in yields were totally ignored. All is to be sacrificed on the altar of global warming.
All of us see how easily this “study” was knocked down, and one wonders why someone….anyone, who reviewed this study prior to publication wouldn’t have seen the weakness of the data. My God, anyone with any common sense knowledge could see the problems that are rife in this study.
Truly, this is a sorry time for science, but especially science in the Western World, and it saddens me, but more importantly is dangerous. The vast majority of progress we have made in the Western World over the past 300 years can be attributed to science, and to see science so corrupted by crass ideology like global warming and all its spawn is to see firsthand the decline of civilization.
As an add-on to the above it would seem that many of the test areas are subsistence farming areas and some of them certainly very remote and unlikely to deliver any sort of consistent yield data accurately. The best and most intensively farmed areas, the maize triangle in South Africa is not represented at all. I grew up on a farm in that area (Ventersdorp) and my family has been farming maize there for over 100 years. Meticulous records are kept about seasons and yields, droughts and floods, weather and so on. Not only them but probably most of the thousands of other old established family farms as well. Where better to go and do some serious and meaningful research? Just have to ask really, the records are there because these farms are managed as serious businesses and everything is monitored.
But no, lets do this on the edge of deserts, mountainous areas and in the middle of protected nature reserves (check Google Earth). Areas where despots rule, access is difficult and the subsistence farmers use draught animals. Where fertilizer is scarce or unobtainable, records are sketchy or non existent and folk will tell you what you want to hear.
“Yes sir, it is the fault of the global warming sir, and we would like you to pay us lots of compensation money sir. Bah humbug.
Doug in Seattle says:
Who funded the study? From what I understand NSF requires that the conclusions for the study be part of the proposal.
Doug,
Please tell me you were being sarcastic and I just missed it.
Without being too detailed…
I’ve a MS in Agriculture. Soils were my study area. Many of the previous comments were spot on regarding at least the test plot presented in the photo at the beginning of the post. The highly oxidized, likely highly weathered, frangible, medium texture soil will have low cation exchange capacity (it just won’t hold many nutrients even when added). This is, unless it is treated with lime or gypsum and “green manure” crops are grown intensively to increase the organic content of the soil, the cyclical nature of the growing season that does not include a winter which halts the action of fungi and bacteria on reducing the dead organic matter to CO2 and H2O will result in a cronic poor soil conditions for food crop production. This is especially true of one such as corn which has a higher soil nutrient requirement than others more adapted to tropical soils such as manioc, casava, possibly sweet potatoes, and others. I’m struggling with this love affair with corn. If they really want to grow corn in these poor soils, why not add the ashes from all the dung cooking, bone meal (as there are plenty of large herbivores), put a fish about 6″ beneath each deeply planted seed, and pray for rain.
Labor intensive? Absolutely
Nutrients for the corn? Absolutely
Did these data just presented require a MS in Agriculture or PhD in Environmental something or other? Nope, I learned this from Granny – she learned it from generations of folks for whom schooling was a luxury unnecessary to farming and logging in SE Louisiana.
They were growing sustenance on highly weathered soils abused by cotton farming for generations. They knew the soils were poor, they learned what made things grow by observation, trial and error, etc. The weeds at the edges of the ash heap grew taller and greener. The patch of grass growing after the cow patty rotted away was taller and greener. The old ant mound finally settled back flat was growing taller and greener grass. So on and so forth, they applied observations to getting more collards, okra, peas, beans, tomatoes, potatoes, corn, curcurbids, etc. out of the ground and into their stomachs.
My next statements may raise some hackles, but I think they are important to ponder. Is the starvation in many third world countries not a product of “relief efforts”? Has the injection of free food (energy) and discouragement of subsistence lifestyles created a demon? Through the massive shipping of food into these historically sparse regions of the world we have encouraged population explosions that were not possible before. Would not the training and education of a native population of agronomists, engineers, and teachers been a better approach in retrospect? They could have learned how to use the local resources for their own people then passed the lessons learned to the next generations. This would have followed the model of Europe, the USA, Australia, and now many SE Asian countries. I do not disagree that we (“the west”) have created the monster and are now responsible for it, but is the lesson now learned or ignored? Can we correct the problem, or is the corruption of socialism and communism so entrenched as to be irreversible?
Willis, where do I start with this?
Averaging min/max and putting an artificial 30 C figure is irrelevant to corn yield from a physiological perspective. This study is similar to climate research where people with absolutely no knowledge background begin number crunching. GIGO. The intricacies of that average are what is important (as in humidity, elevation, local climate, grid smoothing, measurement siting, etc in global temp averages). This issue has been studied hundreds of times before, but perhaps not in Africa. For non-imaginative scientists in the “publish or perish” scenario, replicating this study in Africa was an easy fix.
Corn, being a C4 plant, fixes photosynthate in a routine fashion up to about 90 F. At about 93 F (variation is due to varieties), the chloroplasts “shut down” and the stomates close. In between those values is a somewhat inverse logarithmic decline.
During pollination, however, pollen function is inhibited at significantly lower temperatures, which is probably close to the 86 F number they picked as a descriptor. If temps above that occur during pollination, you will get unfilled ears. If you’ve ever purchased sweet corn with missing gaps within the ear or at the end, it is a response to unfertilized florets (and there is an interaction with water availability). Therefore, this study actually indicates that when temps are averaged, and that average is above ~86 F one of two possibilities has occurred;
1. The daytime high was greater than ~93F and carbohydrate synthesis was inhibited.
OR
2. The daytime high was above 86F AND the corn was at the pollination stage (silking).
(or both)
The additional data you displayed is in agreement with this interpretation. The southern TX corn is a short season corn. You can buy corn varieties with maturity dates anywhere from ~70 day to 120+day. This means that the time it takes from planting to black layer maturity is X days. The folks in south TX plant a short season corn so that plant pollination occurs during a period of the growing season when temps normally do not go above an absolute value (for that variety) that may cause sterility.
I should add that yields generally increase with longer growing season. So to pick a shorter season variety will necessarily limit yield in itself. The issue in question here is then, are the farmers in Africa adept in picking varieties that are appropriate to the environmental parameters encountered in a “normal” growing season. We don’t know. Certainly, ~.5C AGW has not affected yields directly, especially when the data shows that most of that temp increase has been shown to be mostly associated with warmer winter and shorter winters (later frost-free date). Obviously, the tendency for farmers to view the last season as “average” (similarly to climate scientists) precludes their decision to plant a longer season corn for increased yield potential, but possible susceptibility to hot days at the wrong time.
Thanks for bringing this up. I rarely get the opportunity to discuss something in my field. ;~P
I’m an info-geek and a former farm kid from the edge of the dark green belt in SW Ohio. I understand what it takes to grow corn. Summary: ‘All the above’.
The study really sux and I appreciate what Willis does but the real key is not in the math but a compilation of all the empirical perspectives in these comments.
The real kicker is in Zimbabwe’s history; even a midwest guy who read the news knows that Rhodesian farmers knew what they were doing, before the country was ruined by ‘democratic practices’.
Browsing the original paper it’s obvious its perspective pointed to a foregone conclusion.
Which is moot when the history of the region is ignored. What’s needed is for an old style agronomy prof to do the study.
To PRD , above.. Yay!
My next statements may raise some hackles, but I think they are important to ponder. Is the starvation in many third world countries not a product of “relief efforts”? Has the injection of free food (energy) and discouragement of subsistence lifestyles created a demon?
I once encountered a liberal thinker on some forum who declared free markets dont work and cited a three page essay about the typical victim third worlder in Haiti who could no longer grow corn because of nearly free US imports.
When I pointed out that US corn exports especially under US aid auspices were hardly free market, he had to fall back on the typical lib gibberish we all know so well.
I told him to vote for politicians who would end ALL subsidies of everything and of course THEN he pointed out the ‘poor farmer’ and ‘agribusiness’ influences.
Indeed.
And those progressives can still be tied in knots when you advocate against ‘big biz’ for a truly free market.
Tim Folkerts at March 14, 2011 at 8:17 pm,
Try and uyse a little common sense please. Go back to your first reference and note what counties used irrigation and which counties did not. Look at the difference in yields.
That is the key to growing corn. Having plenty of water available especially on hot days.
The soil is an important aspect of holding water so the corn does not dry out. With good soil and plenty of water, the corn loves hot temperatures.
Willis Eschenbach says:
“Southern Texas is at 26 North. The bulk of the study sites are around 20 South. Neither one strikes me as particularly tropical. And yes, it gets damn cold at night in southern Africa.”
The African sites stretch from ~10 °N to ~30°S. The tropics are defined as from 23.4378°N to 23.4378°S. This includes most of the African sites (excluding South Africa) and excludes Texas. In the tropics you do not get the variation of insolation, day length, and seasons as you do in temperate zones; so how do you vary the growing season?
As a Phd student working on my Crop and Soil Science, I am just amazed at the amount of bad papers and science out there. It does not take much to satisfactorily debunk many claims of crop failure. This is why I never reference ‘climate’ articles… and never will so long as I am able.
Willis’ introduction includes:
“Their conclusion? When it gets above a certain temperature, maize growth quickly slows, and it’s worse when it’s dry.”
Taphonomic says:
March 15, 2011 at 9:00 am
“The African sites stretch from ~10 °N to ~30°S. The tropics are defined as from 23.4378°N to 23.4378°S. This includes most of the African sites (excluding South Africa) and excludes Texas. In the tropics you do not get the variation of insolation, day length, and seasons as you do in temperate zones; so how do you vary the growing season?”
Are you suggesting that their claim about temperature should be restricted to the tropics? Or maybe you are suggesting that their study should be extended to take account of differences between tropical and temperate zones?
Ric Werme says:
March 15, 2011 at 4:40 am
Dave Wendt says:
March 15, 2011 at 1:57 am
BTW, someone in another comment mentioned the old rule of thumb that corn needed to be “knee high by the Fourth of July” to insure a good crop. I’m afraid that has become obsolete. Nowadays it’s more like “head high by the Fourth of July”, unless you’re a hot prospect for a low post spot in the NBA.
I’ve never seen corn head high here in New Hampshire by the 4th. We’re lucky to get knee high. Not surprising given the latitude and the 14″ of snow on the ground (somewhere around 35 cm).
Though it was admittedly not entirely clear from the comment, my BTW was meant as an addendum to my previous comment about corn growing in S. Minnesota and Iowa. If you should find yourself driving through those areas of a late June and observe many corn fields struggling to make knee high, you might want to take a flier on some corn futures, betting on higher prices in the Fall. Of course, I wouldn’t use any money that you couldn’t afford to kiss goodbye, because old Mother Nature has had a long term relationship going with her boyfriend, a certain Mr. Murphy.
Dave Springer says:
March 15, 2011 at 4:46 am
Thanks, Dave, for reminding us that there are mechanical constraints that affect where corn is grown commercially as well as climate constraints. In some parts of the world these include things like roads, transportation facilities, and the like.
And thanks to everyone for the interesting comments. Like I said, I love studying and writing about the climate because of the amount I learn doing it. Last week I didn’t know anything about corn, now at least I know a few things. One step at a time …
w.
WeatherBell shows it’s rainy season, get your seed maize ready;
Malawi 78-76*, Namibia 70 -66*, Swaziland 73-71, Zambia 65-63*, Zimbabwe 65-63*, Kenya 67-66*, Tanzania 66-65*, Mozambique 81-80*. But up Niger way it’s still a delightful dry 84-76*, but they (and their neighbors) go for planting millet anyway.
E.M.Smith, that was a hoot, as we say here in Texas, I heared dat! I gave the same talkin to my girls boyfriends and they had a look of oh shit on thier faces, needless to say my girls have never had a problem with any man thinking they can do them harm!
Taphanomic, growing seasons are different in any part of the globe depending on weather,water resources, soil management! The scientist did not not use real farmers or agricutral science in the study, they just seemed to go to the farms take a few pictures, then go get the data from far off weather stations, and sit down and write. there is more to getting good crops than just planting and sit back and harvest and these scientist do not seem to have any idea, my suggestion to you is to go back and reread the comments espesicially the ones from farmers of corn and you will see just how BAD of a study this really is!
Willis,
I’m not sure your definition for GDD is correct. The formula I’m familiar with for calculating GDD is as follows. Note that temps above 86 degrees F do not impact the formula at all. It is assumed in the formula that temps above 86 F for max temps do not harm the corn but don’t help it either. So by the definition of GDD the only thing that affects yield would be higher min. temps at night.
The formula for calculating growing degree days is to add the daily high temperature (86°F maximum) and daily low temperature (50°F minimum), divide the result by 2 and then subtract 50. The answer represents the heat units for one day.
GDD = [(daily high + daily low) ÷ 2] – 50
Example 1:
83°F (daily high temp); 63°F (daily low temp) 83 (daily high) + 63 (daily low) = 146 146 ÷ 2 = 73 73 – 50 = 23 GDD
Example 2:
95°F (daily high temp); 70°F (daily low temp) Since the daily high temperature is greater than
86°F, 86°F will be used as the daily high temperature. 86 (daily high) + 70 (daily low) = 156 156 ÷ 2 = 78 78 – 50 = 28 GDD
Producers can use a thermometer that reads both maximum and minimum temperatures to calculate and record GDD for their crop.
Theo Goodwin says:
Are you suggesting that their claim about temperature should be restricted to the tropics?
The article states “Roughly 65% of present maize-growing areas in Africa would experience yield losses for 1 °C of warming under optimal rain-fed management”
While they don’t specify where this 65% is, I would interpret Figure 3d as indicating that that it is in the tropical regions.
Craigo says:
March 15, 2011 at 4:57 am
This is my constant issue with these kinds of articles. They assume that if adverse things occur, people won’t immediately change their actions and habits to counteract it and indeed, in some situations, take advantage of it. Warmer weather? Grow warmer weather crops, or grow the same crops earlier, or …
I read today that they’re working on developing salt-tolerant avocados. Avocados are pickier than humans about their water. I have no doubt it will be accomplished sooner or later. Thats what humans do, we’re not slaves to the weather such that we’ll sit and watch yields decline and not take action.
w.
Why did they bother to go to Africa for this study? I would imagine that one could go the Ag departments in any of the Midwest state universities and find studies relating corn yields to every conceivable variable.
Willis Eschenbach says:
“Thats what humans do, we’re not slaves to the weather such that we’ll sit and watch yields decline and not take action.”
Ironic. I’ve been pointing out that taking these actions (and increasing yields) are the main things that Norman Borlaug and CIMMYT have been doing for decades.
Here’s a link to an earlier (2007) study by Lobell on “global scale climate-crop yield relationships and the impacts of recent warming ”
http://iopscience.iop.org/1748-9326/2/1/014002/fulltext
It was something of a data trawling exercise looking at possible months of temperature data versus yield- however the best R2 combination for maize seems to be to behave rather differently to the lower R2 combinations. -[Their figure 5 ].
Physics Major says:
March 15, 2011 at 11:34 am
Why did they bother to go to Africa for this study? I would imagine that one could go the Ag departments in any of the Midwest state universities and find studies relating corn yields to every conceivable variable.
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GOOD LORD YES!! And then some.
In reading through the post (which I much enjoyed) and the responses, I felt that something I had read damned the Lobell et al paper out of their own mouths. It was in Anthony’s previous discussion (linked to by Willis) and the three relevant paragraphs are repeated immediately below:-
Open quote.
While the crop trials have been run for many years throughout Africa, to identify promising varieties for release to farmers, nobody had previously examined the weather at the trial sites and studied the effect of weather on the yields, said Lobell, who is an assistant professor of environmental Earth system science.
“These trials were organized for completely different purposes than studying the effect of climate change on the crops,” he said. “They had a much shorter term goal, which was to get the overall best-performing strains into the hands of farmers growing maize under a broad range of conditions.”
The data recorded at the yield testing sites did not include weather information. Instead, the researchers used data gathered from weather stations all over sub-Saharan Africa. Although the stations were operated by different organizations, all data collection was organized by the World Meteorological Organization, so the methods used were consistent.
End quote.
The second quoted paragraph really says it all. It’s my experience that it is hard enough to get valid results from an experiment that you have actually designed to achieve a stated objective, let alone from one that was carried out for ‘completely different purposes’ and one in which the original observers did not bother to record any local weather information.
I also empathise with Anna. In my darker moments, I often feel that western civilisation is sowing the seeds of its own self-destruction especially where politicians are contaminating science for their own short-term gains and in feeling that the pursuit of knowledge etc. has ‘to be made easy, or at the very least, FUN’.
I could go on but that’s enough for now and it’s nearly time for bed, anyway.
Charlie
E.M.Smith says:
March 15, 2011 at 1:21 am
Jeff Alberts says:
2. Corn is only a minor crop in many regions within that general preferred temperature band. So obviously, there’s other factors.
For those who speak English, that would be “there are other factors”. 😉
Well, to quote my Texas Uncle:
“Well, son, we won’t go holten that ‘gainst yah. There’s been lotsa facturs ’roundt hearsabouts, and spiiken Anglish aint won we been known for holten ‘gainst a fella.”
Soes if yous ‘ill just stop t’ holler ‘n about it, we ken prolly get you’all ‘t pass with’n out too much trouble….
‘Corse, if you’all are gonna make a fuss ’bout it, well, let me introodoose you to some Texas “Culturall Art E Facts”… This ‘un here, it’s calt a “Three Fifty Sev’n Magnum” and this other ‘un, it’s calt a “Foorty Five Colt”…
😉
I “married in” to a Texas Family. It has been ‘interesting’…. ect
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Old Son lemme jest say that yer right as rain. Jest one little nit ta pick wit ya.
Stead of interesting….should’a been “INtrastin.” LOL
Denny
I should have added to my previous comment re the Lobell et al. paper that surely, to study the effects of ‘climate change’, you have to define somewhere what you mean by ‘climate change’
Perhaps the authors did as I have not had access yet to their paper.
Charlie
Willis — it appears that you used a different “degree day” than did the article.
They use some sort of hourly summation, assuming sinusoidal variation of temperature from min to max over the day.
Their method is definitely not the simple degree day calculation using (Tmax+Tmin)/2 – Tbase. It doesn’t seem to be the same as the Baskerville emin version of degree days, although it is closer to that.
See equation 2, on page 7 of http://iis-db.stanford.edu/pubs/23138/Lobell_2_11_NatureClimateChange.pdf
The equation seems a summation at hourly intervals over the entire 3600 hour (150 day) growing period. So the summation is really degree-hours as written.
——————————–
I note that the key supporting reference on effect of 30C+ temps on corn also appears to be climate change related: 13 Schlenker, W. & Roberts, M. J. Nonlinear temperature effects indicate severe damages to U.S.
231 crop yields under climate change. Proceedings of the National Academy of Sciences 106, 15594-15598 doi:10.1073/pnas.0906865106 (2009).
Physics Major says:
“Why did they bother to go to Africa for this study? I would imagine that one could go the Ag departments in any of the Midwest state universities and find studies relating corn yields to every conceivable variable.”
Two words: ground truth. How could an Ag department in any of the Midwest state universities duplicate tropical climates and lack of seasonality? You go to were these things occur to get the answers. See: http://www.cimmyt.org/
cirussell says:
March 15, 2011 at 11:13 am
If their formula were for growing degree days, you’d be correct. But they are calculating degree days over 30°C, which is why they call it GDD30+.
Thanks,
w.
We grow a lot of corn in Honduras, and corn is very popular in Mexico. Yields are low here, about 1/4 that of the U.S. Corn Belt. But poor rocky soil, low fertilizer and pesticide use surely contribute to a lot of the difference.
Charlie A says:
March 15, 2011 at 1:22 pm
Yes. I used the standard calculation, (daily temperature max + min)/2, because I didn’t have hourly temperatures for the Edinburg site in Texas. In their case, they fit a spline to the actual max and min and calculate it hourly … I don’t think it makes much difference, although I haven’t checked that. Hang on …
OK, I just took a look. It’s interesting, there is some difference. I made up some pseudo-data, 24 hourly pseudo-temps per day. Sinusoidal, of course. I added to it a much slower sinusoidal curve to represent the warming and cooling during summer. Then I looked at the degree-days figured two ways – the way I did it with average daily temperature, and their method.
The way they did it (calculate “degree-hours over X° C”, and divide by 24 hrs/day) gives a greater number of degree days than the usual method (using the daily mean temperature rather than hourly mean temperature). This is true for all values of X. The larger the number of degree-days, the smaller the effect. When temperatures are lower, of course, the mean temperature drops below 30°, so no degree days are recorded. But the hourly temperatures still can go over 30°, so using their method fractional degree-days are recorded. These can add up depending on the exact data in question.
So … where I measured 136 growing season degree days over 30°C in southern Texas, their method would give a larger number. How much larger? Unknown, but from my simulation likely around 25%.
Thanks for bringing that up, I’d been meaning to look into that.
w.
PS – I disagree with their method, in that it makes up data under the assumption that the daily temperature swings are sinusoidal. While in general this is not too far from true, often it is not the case at all. This is particularly true in the tropics. There, mornings are clear and the temperature rises fast. Afternoons are cloudy, the temperature rise flattens way out.
In addition, drawing a sine wave through a bunch of data can give you good numbers.
But drawing a sine wave through the extreme values is likely to give you bad numbers … and nature specializes in extreme extremes. Temperatures don’t vary smoothly. You have a day where it’s overcast all day. Then at around 2 PM, the clouds disappear and the hot sun shines down. For that hour it’s lovely and warm. Then the clouds come over again, and the party moves indoors to get out of the cold wind that springs up.
Now, if you draw a sine curve through the maximum temperature point of the day, it will look like a nice sunny warm day, warming to a peak and then slowly cooling down. But in fact, the temperature flatlined during the day, except for one large but short spike in temperature at 2 PM when the clouds broke.
As a result, putting a spline curve through the extremes of a dataset is pretty much guaranteed to distort the data. Better than nothing, I guess … but I just don’t like manufactured data.
safariman says:
March 15, 2011 at 8:04 pm
Thanks, safariman. The GAEZ study is great for looking at these questions. Take a look here at the GAEZ estimate of possible yields for maize in Central America. Honduras is inherently not a great spot for maize. The Yucatan is much better.
w.
The Romans must have starved to death while all around them empires and civilizations flourished. /sarc
Roman warm period as warm or warmer than the our current period.
http://www.jstor.org/pss/124215
http://www.pnas.org/content/early/2010/03/02/0902522107.full.pdf
Just to remind ourselves that there is nothing much new that comes around in human experience, I offer the following extract from published material.
My immediate source is ‘Planning of Experiments, D. R. Cox, John Wiley & Sons, 1958 (Fifth Printing December 1966), Library of Congress Catalog Card Number 58-13457’. I am somewhat concerned that I do not have written permission from the publisher to reproduce such material and I rather suspect that 44 years is not quite long enough for copyright to have lapsed.
The example given by David Cox is on page 10 of the referenced publication and is as follows.
“Student” (1931) mentions some experiments done by the Irish Department of Agriculture in connection with the introduction of Spratt-Archer barley. This was almost everywhere a great success; yet in one district the farmers refused to grow it, alleging that their own native race of barley was superior. After some time the Department, to demonstrate Spratt-Archer’s superiority, produced a single-line culture of the native barley and tested it against the Spratt-Archer in the district in question. “Student” reports that to the Department’s surprise the farmers were perfectly right; the native barley gave the higher yield. At the same time, the reason became clear; the barley in question grew more quickly and was able to smother the weeds, which flourished in that area; Spratt-Archer, growing less strongly to begin with, was, however, the victim of the weeds. Thus the original experiments, carried-out on well farmed land, were definitely misleading when their conclusions were applied elsewhere.
This little piece lends support to many of the points raised in this thread. It also shows a refreshing glimpse of the willingness of some bureaucrats in earlier times to attempt to demonstrate their case using a further properly organised study – rather than just shouting ever more loudly.
Some readers will no doubt recognise the name “Student” as he of ‘t-distribution’ fame. A century ago, as W. S. Gosset, he was working for the Guinness Brewery Company, but apparently in order to safeguard his employment there he felt obliged to publish his statistical writings under a pseudonym. Whether this was because of some dispute over intellectual property rights or other similar reason, I know not.
What does seem now to be likely is that many people are only able to work on projects, and to publish suitable results therefrom, as agreed by their employers. Step out of line and here’s your P45 (an HMRC tax document provided to people leaving employment in the UK). In principle, this has probably always been the case but it will be interesting to see if the work of the CAGW ‘climate scientist’ lobby stands the test of a century as has “Student’s” work.
Mod: Thanks for the note re latitude of Texas. My point was Swaziland is as far south as Testas is north. Couldn’t reply right away – been travelling from Ulaanbaatar to Waterloo. Takes time…
Tim Clark in his good piece says:
“This issue has been studied hundreds of times before, but perhaps not in Africa.”
As can be noted from seveal contributions above, there is a huge amount of agricultural research going on in Africa. For example, the local development of high lycene maize with a long shelf life in Ghana – global level contribution to the food supply.
One programme alone at the Malkerns Research Station in Swaziland 25 years ago produced 20 local MSc’s just for that task. The popular Western picture of African agriculture may locusts eating a shrivelled millet stalk in Mali, but it is very far from the truth in most places.
Dumping subsidised Western (including European) maize and milk products has been particularly damaging to farming throughout the continent. In a free market Africa could outproduce the ROW (rest of world).
Maybe they have failed to properly isolate the variabel?
grayman says:
“The scientist did not not use real farmers or agricutral science in the study, they just seemed to go to the farms take a few pictures, then go get the data from far off weather stations, and sit down and write.”
I don’t believe that is correct. For decades CIMMYT has set up a world wide network of trial farms to improve quality and quantity of grain. They have succeeded. The published article at http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1043.html
states: “In this case, we focus on field trials for tropical maize conducted in Africa in 1999–2007 on a network of 123 research stations managed by the International Maize and Wheat Improvement Center (CIMMYT), National Agricultural Research Programs and private seed companies (Fig. 1). The original purpose of these trials was to test new varieties across a range of environmental conditions, to identify robust lines for release to farmers.”
Thus, these trial farms are in part set up by one of the author’s organization (CIMMYT).
They aren’t afraid to get their hands dirty. For more info see: http://en.wikipedia.org/wiki/Norman_Borlaug
Further to my earlier comments.
Wouldn’t you just know it?
“Student’s” 1931 paper about the differences in barley yields according to the Irish Department of Agriculture and farmers in a particular district was entitled ‘Agricultural field experiments’ and published in ‘Nature, 127,404’. It was later reprinted in “Student’s” collected papers. Cambridge, 1942.
I wonder if Lobell et al. cited “Student’s” paper in their study.
Loved this quote, “When it gets above a certain temperature, maize growth quickly slows, and it’s worse when it’s dry.”
Well, of course, quickly slowing is much worse than slowly slowing or quickly speeding up. But what about when it is slowly speeding up? Perhaps that’s as bad? Or maybe it’s better. I’m not sure if it makes me anxiously sanguine about the whole thing, or indifferently partial. Anyway, although though the observation is obviously profound, I find it to be seriously ludicrous.
R. Craigen says:
March 16, 2011 at 8:03 pm
Is this a serious complaint, or not? If so, we say things like “I was late noticing the police car, so I quickly slowed my car down to avoid a ticket. I would have slowed down faster, but I was afraid I’d squeal my tires.” The meaning of that seems quite clear … I’m afraid I don’t see the problem. If you’re serious. If not, ignore alien orders.
w.